import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } enum F_INF = sqrt(0.81L / (1.0L - 0.81L)) / (0.9L / (1.0L - 0.9L)); real F(int n) { real numer = 0.0L, denom = 0.0L; foreach (i; 1 .. n + 1) { numer += 0.81L^^i; denom += 0.9L^^i; } return sqrt(numer) / denom; } real f(int n) { return (F(n) - F_INF) / (F(1) - F_INF) * 1200.0L; } real g(real x) { return 2.0L^^(x / 800.0L); } real gInv(real y) { return (log(y) / log(2.0L)) * 800.0L; } void main() { try { for (; ; ) { const N = readInt(); auto RPerf = new real[N + 1]; foreach (i; 1 .. N + 1) { RPerf[i] = readReal(); } real numer = 0.0L, denom = 0.0L; foreach (i; 1 .. N + 1) { numer += g(RPerf[i]) * 0.9L^^i; denom += 0.9L^^i; } const ans = gInv(numer / denom) - f(N); writefln("%.0f", ans); } } catch (EOFException e) { } }